The fast-spreading Centaurus strain of Covid-19 could pose a problem for health authorities once travellers return from summer holidays, a top virologist said.
Omicron subvariant BA.2.75 has been rapidly spreading across India since it was first recognised there two months ago.
It has since been recorded in other countries across Europe and in the US.
Named after a faraway star constellation during a random tweet about rising infection numbers, the Centaurus name for the latest variant of the virus has stuck.
On Thursday, the World Health Organisation warned that Covid cases were also rising in the geographical area it classes as the Eastern Mediterranean, which includes the Middle East and parts of North Africa.
On average, there are 18,000 new cases and 31 deaths in the region. Under-reporting is common and figures could be much higher.
It is not known if it is likely to have a higher death rate than previous variants, but doctors said the variant is already proving more transmissible judging by the speed at which new infections are reported.
Dr Matthew Binnicker, director of clinical virology at the Mayo Clinic in Rochester, Minnesota, said rapidly spreading infections were likely to continue in the months ahead, with more patients requiring hospital treatment.
“It’s likely that the large and dense population centres in India are contributing to the rapid spread of BA.2.75 [Centaurus],” Dr Binnicker told The National.
“If the spread follows prior trends, it is likely to also cause surges in the UK and the US in coming months.
“Given global travel, all countries should be aware of the rapid spread of BA.2.75 and be taking steps to reduce the number of overall infections.
“It is important to ramp up vaccinations and ensure those who are eligible for a booster receive their additional dose, which will help to reduce infections.
"And, most importantly, the overall number of people coming down with severe disease, requiring hospitalisation and dying from Covid-19.
“There is a trend of increased hospitalisations in many countries, but this is likely a reflection of the higher rates of transmission rather than the new variants causing worse disease.”
Centaurus has mutations in the spike protein of the virus; the spike protein is the part that helps the virus bind to the surface of human cells, and it is also targeted by most Covid-19 vaccines.
So far, the variant does not appear to carry any unique symptoms, while anyone who develops a fever, cough, sore throat and headache should be tested.
Rising case numbers, fewer deaths
Doctors said the virus still had the potential to cause complications in patients already in hospital being treated for other conditions.
“The mutations in BA.2.75 are allowing the virus to be spread at a higher rate compared to other variants,” Dr Binnicker said.
“There is also concern that the mutations in BA.2.75 may allow the virus to evade the immune response generated by either vaccination or prior infection.
“Currently, the number of BA.2.75 infections in the United States and the UK is believed to be low; however, that may change over the next few months.”
In the UK, scientists writing in the British Medical Journal said Covid-19 was pushing the NHS close to collapse and was unlikely to settle into a seasonal pattern, as seen with influenza.
Hospital admissions in the UK of patients with Covid-19, but not necessarily admitted as a result, averaged slightly above 9,000 a week, against just below 6,000 last year and just under 7,000 in 2020.
Meanwhile in India, a seven-day average of 2,224 new cases of Covid-19 were reported on May 18, but that had climbed to 18,588 on July 18 as the Centaurus strain circulated in densely populated areas.
In the US, reported infection numbers have risen to a weekly average of 128,849 on July 18 compared with 98,094 a month earlier.
“This current trend shows that the Covid-19 pandemic is far from over,” said Dr Ahmed Al Mandhari, the WHO regional director for the Eastern Mediterranean.
“We try to forget Covid-19, but the virus has not forgotten us."
The University of Washington’s Institute for Health Metrics and Evaluation estimated for every reported new case of Covid, there were likely to be seven more going unseen.
Prof Paul Hunter, an expert in infectious diseases at the University of East Anglia, said while BA.2.75 was likely to become the most dominant variant, a return of travel restrictions was unlikely .
“Other variants have looked threatening, but faded after a month or so,” he said.
“This is an escape mutation in that it can get around prior immunity, but not all of it because there are different degrees of protection that people will have.
“An interesting development has been hybrid immunity in people who have had three vaccines and the virus itself.
“That shows you have a better immunity even to new variants we don’t even know about yet.
“In the UK, despite serial waves of infections, the numbers with severe disease is generally lower in each wave.”
Prof Hunter estimated that about 90 per cent of the UK population would have had some kind of exposure to infection, increasing their natural immunity.
Combined with a widespread vaccination programme, this latest variant posed little cause for concern of more serious disease, he said.
“No matter how good control measures are, unless you stay in lockdown and keep your borders closed permanently, these viruses will eventually appear in waves,” Prof Hunter said.
“You can expect to see a surge in cases with people returning from summer holidays.
“Potentially, I could see a return to pre-flight testing but I’m not sure that will happen.
“There may be some pressure applied by governments to reinstall these measures, but their value is a lot less than they were a year or so ago.
“There have not been that many outbreaks that have occurred on an aircraft that we know for sure."